Originally Posted by Alex - A2hosting
The server itself, cPanel license, backup software license, other features to remain remotely competitive such as Softaculous are just a few that comes to mind.
Sure you might not get issues with only 3 master resellers but at scale this isn't going to really work, it can only take a few fast growing master resellers to start causing issues.
Yes on a large scale if will cause issues as you will soon lose control of how many and what sites are being hosting on your servers and you only have any contract with the original MR.
Even my MR are limited to only 20 cpanel accounts initially, if they need more they would have to open a ticket and request more accounts